: Uveitis is a major cause of blindness in the United States. Pars planitis is a well- defined disease subset of uveitis. The cause of pars planitis, as well as other forms of uveitis, is frequently unknown. The PI has identified a 36 kDa protein (p-36) which is markedly increased in the peripheral blood of patients with active pars planitis. Recent results from the laboratory suggest that p-36 is a part of a larger protein which is approximately 95 kD (p-95) in size. The identification of proteins which may contribute to the pathogenesis of pars planitis would be a major advance toward its treatment and possible cure. The specific aims of this proposal are: A. To correlate levels of p-36 and p-95 with clinical disease in pars planitis. B. To determine the structure of p-95. C. To study the tissue distribution of p-95. Quantitative assessment of p-36 and p-95 levels in patients; blood may be of value in both monitoring disease activity and guiding treatment. The PI hopes that the proposed studies will allow the uncovering of important information concerning the mechanism of ocular inflammation in pars planitis, and possibly, to design more effective treatment for this disease.